The output transistors can be BC548 and BC558. The circuit is from a 1975 documentation showing a frequency response from 90 Hz to 12.5 kHz.
This circuit was taken from a Popular Electronics from the 1990s. The circuit triggers a relay that...
The transformer inf this circuit is a 6 or 9 V unit and diodes 1N4002. The filter capacitor is 2...
This circuit causes a relay to oscillate generating a signal that turns into high voltage in a...